Human Rights Watch accused the Saudi-led coalition fighting in Yemen of war crimes on Tuesday, saying its air strikes killed 39 civilians including 26 children in two months.

The rights group said five air strikes hitting four family homes and a grocery store were carried out either deliberately or recklessly, causing indiscriminate loss of civilian lives in violation of the laws of war.

The coalition has repeatedly denied allegations of war crimes and says its attacks are directed against its foes in Yemen's armed Houthi movement and not civilians.

Yemen has been torn by a civil war in which Yemen's internationally-recognised government, backed by a coalition supported by the United States and Britain, is trying to roll back the Iran-aligned Houthi group which controls most of northern Yemen, including the capital Sanaa.

"The Saudi-led coalition's repeated promises to conduct its air strikes lawfully are not sparing Yemeni children from unlawful attacks," said Sarah Leah Whitson, Middle East director at Human Rights Watch, in a statement.

"This underscores the need for the United Nations to immediately return the coalition to its annual 'list of shame' for violations against children in armed conflict," she said.

On 4 August, coalition aircraft struck a home in Saada, killing nine members of a family, including six children, ages three through to 12.

On 3 July, an air strike killed eight members of the same family in Taiz province, including the wife and eight-year-old daughter, the organisation said.

HRW said it interviewed nine family members and witnesses to five air strikes that occurred between 9 June and 4 August, and did not detect any potential military targets in the vicinity.

The war has killed more than 10,000 people, displaced more than three million and ruined much of the impoverished country's infrastructure.

The Saudi-led coalition was formed in 2015 to fight the Houthis and army troops allied with them who have fired missiles into the kingdom.

HRW called on the United Nations Security Council to launch an international investigation into the abuses at its September session.

On Monday, the UN said it has verified 5,144 civilian deaths in the war in Yemen, mainly from air strikes by a Saudi-led coalition, and an international investigation is urgently needed.